1. Field of the Invention
The present invention relates to a tire noise reduction device. More specifically, the present invention relates to a tire noise reduction device which allows rapid and reliable tire sealing when a pneumatic tire runs over a nail or the like and is punctured, without deteriorating the durability of a noise absorbing member attached to the inner surface of a tread portion of the tire.
2. Description of the Related Art
A resonance sound is generated in a pneumatic tire due to the vibration of the air in a tire cavity during running. This cavity resonance sound is known to make a vehicle occupant uncomfortable when transmitted into the vehicle compartment. Conventionally, in order to reduce such a cavity resonance noise generated in the tire cavity portion, it is known to dispose a noise absorbing member made of a porous material on the inner surface of a tread portion (see, for example, International Publication Nos. WO2005/012007 and WO2006/088000 and Japanese patent application Kokai publication Nos. 2006-224928 and 2007-237962).
Meanwhile, there is a tire sealing method for a case where a tire having run over a nail or the like during running is punctured with a through hole formed by the nail or the like in the tread portion. In the method, a liquid tire sealant is poured through an air injection valve and caused to flow into the through hole by the air pressure. Thereby, the through hole is sealed.
However, the aforementioned tire that has the noise absorbing member disposed on the inner surface of the tread portion has a problem that the tire sealing operation cannot be performed smoothly even when a liquid tire sealant 6 is poured into a cavity of a tire 3 as shown in FIG. 18. This is because a noise absorbing member 2 hinders the liquid tire sealant 6 from entering a through hole (A) formed by a nail (B) piercing through a tread portion 4. Particularly, in a case where the tip end of the nail (B) does not pierce through an inner peripheral surface 2y of the noise absorbing member 2 as shown in FIG. 18 or where the liquid tire sealant 6 does not reach the inner peripheral surface 2y of the noise absorbing member 2 even if the nail (B) does pierce therethrough, the liquid tire sealant 6 cannot flow into the through hole (A) readily. This makes the operation of sealing a hole of the punctured tire more time-consuming.
Moreover, an air injection valve provided on a rim is located generally on the outer side of the vehicle when the pneumatic tire is mounted on the vehicle. For this reason, in the tire having a noise absorbing member 2 that is disposed around the inner peripheral surface of the tire, a liquid tire sealant 6 poured therein through an air injection valve is likely to be present mostly on the outer side of the noise absorbing member 2 when the pneumatic tire is mounted on the vehicle. Accordingly, when a through hole (A) is formed in the tire on the inner side of the vehicle with respect to the noise absorbing member 2 when the pneumatic tire is mounted on the vehicle, the noise absorbing member 2 blocks the flow of the liquid tire sealant 6. Eventually, no liquid tire sealant 6 flows into the through hole (A).